Electron discharge device of the klystron type



C. E. WARD March 14, 1961 ELECTRON DISCHARGE DEVICE OF THE KLYSTRON TYPE 2 Sheets-Sheet 1 Filed June 5, 1959 km MV INVENTOR. Curtis E. Ward C. E. WARD March 14, 1961 ELECTRON DISCHARGE DEVICE OF THE KLYSTRON TYPE 2 Sheets-Sheet 2 Filed June 5, 1959 INVENTOR Curtis E. Ward United States ELECTRON DISCHARGE DEVICE OF THE KLYSTRON TYPE Filed June 1959, Ser. No. 818,413

12 Claims. 01. 315-5.23)

This invention relates in general to velocity modulation electron tubes and, more particularly, to an improved klystron tube construction.

A velocity modulation device of a novel construction is described and claimed in United States patent application Serial No. 516,096 entitled Electron Tube Apparatus, filed June 17, 1955 by Bernard C. Gardner and George F. Reyling. This earlier patent application discloses a klystron device in which the cavity resonator or cavity resonators are mounted on one vacuum sealed end of the evacuated body of the klystron and extend within the body from said one end such that the electron beam path through the cavity resonator is substantially perpendicular to the body axis. The other tube elements, such as the cathode, are mounted on the body or on a mounting member sealed in the opposite end of the body such that the tube elements extend into the body from said other end, these elements being positioned in cooperative alignment with the cavity resonator. In this manner the cavity resonator may first be mounted within the body and then the other tube elements brought into the body from the other end into cooperative alignment with the cavity resonator, these other elements and their mounting base then being vacuum sealed within the body. The present invention relates to an improved klystron device of this general type.

it is, therefore, the object of the present invention to provide a novel rugged klystron structure which is suitable for mass production utilizing standard, inexpensive tube elements.

One feature of the present invention is the provision of a kystron in which the cavity resonator is mounted on one end'of'the body and directed inwardly of the body in cantilever fashion, other tube elements being mounted on a mounting member in the opposite end of the body and brought within the body into cooperative alignment with the cavity resonator, the cavity resonator being provided withintegral guideways which cooperate with guide plates on the tube element mounting member to correctly align the cathode resonator and tube elements upon engagement within the tube and to firmly hold the cavity resonator against vibration and the like. 'Another feature of-the present invention is a vacuum tube apparatus of the above featured type 'in which a cathode and heater assembly, focus assembly and reflector assembly are mounted on the mounting'member between a pairof insulating plates and a pair of guide plates are also mounted thereon, the. guide plates being fixedly secured between the insulating plates and cooperating-with the 'guideways in the cavity resonator'for guiding the assembly into alignment with thecavity resonator.

Another feature of the present invention is the provision 'of'a novel jklystron device of the first above- -featuredtype wherein the tube. elements such as the cathode, heater, focus electrode and reflector electrode aressecured on a mounting assembly, this mounting assembly, in;turnrbeing mountcdon aconventional stem atent by means of thrust plates or mount supports to carry the force of insertion of the mounting assembly into engagernent with the cavity resonator in the body.

Stid another feature of the present invention is the provision of a novel klystron device in which the evacuated body of the klystron comprises a metallic bulb formed with an end wall, there being an iris opening cut into the end wall and a vacuum sealing window sealed over the iris opening outside of the bulb, the cavity resonator of the device being-secured on said one end within the bulb member and having an opening aligned with the iris opening in the end wall of the metal bulb.

Another feature of this invention is the provision of a klystron device incorporating novel temperature compensation of the cavity resonator for maintaining frequency stability.

Still another feature is the provision of 'a cylindrical shaped klystron body in which the output window is lo-' cated in one circular end of the body, the cylindrical body being adapted for plugging into the end of a circular waveguide adapter device for converting this plug-in type klystron to one suitable for flange mounting on a waveguide output.

These and other features and advantages of the present invention will be more apparent after a perusal of the following specification taken in connection with the accompanying drawings wherein,

Fig. l is a longitudinal cross-section view of one embodiment of the present invention,

Fig. 2 is a cross-sectional view of the embodiment of Fig. 1 taken along section line 2-2 in the direction of the arrows,

Fig. 3 is a plan view of the klystron of Fig. 1 taken from the window end of the body,

Fig- 4is a cross-sectional view of the klystron of Fig. 1 taken along section line 4-4 in the direction of the arrows,

Fig. 5 is a crosssectional view of a portion of the klystron taken along section line 55 in Fig. 2 in the direction of the arrows,

Fig. 6 depicts a waveguide flange adaptor used for converting the plug-in type klystron of Fig. 1 to a waveguide fiange mounting type tube,

Fig. 7 is a view looking into the waveguide adaptor shown in Fig. 6,

Fig. 8 is a view of the device of Fig. 1 showing a waveguide flange brazed thereon, and

Fig. 9 is a partial view of the klystron of Fig. ,1 adapted for use with a tunable external cavity.

Referring now to Figs. 1 through 5 of the drawings there is shown a reflex klystron in which they main body shell comprises a hollow metallic bulb 11 as of, for example, steel, completely closed at one end 12 except for a small, substantially rectangular shaped iris opening 13 therein. A wave energy permeable window comprising a disk of ceramic 14 vacuum sealed to an'annular Kovar frame 15 is sealed over this opening 13 on the outside of the body 11. Also brazed on the outside of the bulb 11 and surrounding the ceramic window 14- and frame 15 is an annular window plate 16 of, for example, steel which serves to provide good electrical contact with theoutput waveguide circuit into which this reflex klystron-is adapted to removably fit during use.

' A cavity resonator 17 is secured, as by brazing, within thebody 11 over the iris opening 13 and extends in a cantilever fashion within the bulb 11. The cavity res-,

as /seas r 2 pensation as described below. A hollow cylindrical drift tube 19 of, for example, steel is secured over the central opening in one of the cavity resonator plates 18 and extends within the cavity resonator, there being a first resonator grid 20 mounted on the end of this drift tube 19'. A second cavity resonator grid 22 is mounted over the central opening in the other cavity plate 18' and, with grid 21, forms the interaction gap in the cavity resonator 17. An accelerator grid 23 is also mounted on the outer side of the first cavity plate 18 over the central opening therein. Each of the cavity resonator plates 18, 18' is formed with an outwardly directed flange portion 24 so that, when placed back to back, the cavity plates 18, 18' form a groove or V-shaped guideway which serves as a guide for mounting and aligning the tube elements within the tube as described subsequently.

A conventional base 25 made of, for example, plastic (not shown in Fig. 1 but illustrated in Fig. 8) having metal prongs 26 embedded therein is secured in the other end of the hollow cylindrical metallic bulb 11 as by crimping into recesses 28. A ceramic stem structure is vacuum sealed within the base end of the bulb 11, this stem structure including an annular metallic frame 29 and a ceramic insulating disk 31 brazed within the frame, the ceramic disk 31 having a centrally disposed opening through which an evacuating pinch-E tube 32 extends, the pinch-oil tube being vacuum sealed to the ceramic disk 31 by means of a metallic collar 330i, for example, Kovar. A plurality of electrical leads 34 are vacuum sealed in the ceramic disk 31, the outer ends of the leads being soldered within the prongs 26, the inher ends extending within the bulb 11 and being connected with the various tube elements in well known manner for applying proper potential thereto for operating this reflex klys tron in accordance with standard theory.

A pair of substantially U-shaped thrust plates or support members 35 made of, for example, nickel, one of which is shown in Fig. 1, are brazed onto the metallic frame 29 and serve to support the tube element assembly within the bulb 11. This tube element assembly comprises two identical spaced-apart plates or disks 36 of an insulating material such as, 'for example, mica,

these disks 36 being fixedly secured together and spaced one from the other by wires 37 and integral eyelets 37' as well as by other structure described below. Each of the plates 36 has a centrally positioned rectangular shaped opening therein, each opening being surrounded by a metallic collar 38 of, for example, nickel, the collar 38 having four tabs 39 which fold under the plate 36 to secure the collar 38 to the plates 36. i

A cathode structure is securely mounted between the plates 36, the cathode structure including a focusing electrode 41 of nickel which is mounted on the plates 36 by means of integral tabs 42 extending through small openings in the-plates and folded over onto the plates. An annular cathode support 43 is secured on the focusing electrode 41, four legs 44 extending from the support 42 and serving to support the cylindrical cathode button 45. A heater retainer cup ddcloses the end of the cathode button 45 and holds the heater 47 within the button, the ends or the heater 47 being electrically connected to two of the support wires 37 which are in turn connected to two of the leads 34.

A reflector 48 is also mounted between the plates 36 by means of tabs 49, the reflector being exactly the same structural member as the focusing electrode 41 with the exception that the central portion of the member is removed to form the focusing electrode,

A pair of metallic guide members 51 (see Figs. 2,

,4- and are secured between the disks 36, these guide members 51 being mounted on tabs 52 extending from the collars 38 through the plates 36. The central portions of two guide members 51 areprovided with elongatedeindentations 53-which serve'as'guides for the guideways -forrned by the flanges 240i the cavity resonator 17.

The cross section configuration of the guide members 51 has a sinuous form as shown in Fig. 2 to provide flexibility in the guide members so that they may be tensioned to tightly grip the cavity resonator flanges 24. The guide members 51 are rigid in the longitudinal direction and thus hold the center of the plates 36 in a secure, spaced relationship. The guide members 51 are also provided with tabs 54 which extend through one of the plates 36 and are fixedly secured to extension tabs on the thrust plates 35.

It is thus seen that the tube element assembly is fixedly secured by means of collars 38, guide members 51, and thrust plates 35 directly to the firm base 29, 31. Each of these supporting elements is a rigid, metallic structure and thus the support is designed to withstand shock and the like. in addtiion, it is noted that the electrical leads 34 are not utilized for support purpose and thus the electrical connection junctions are free from support stresses and the like. This same solid support also serves to firmly hold the cavity resonator by its edges in the grip of the guide members 51, the cavity alsobeing secured as described above to the wall of the body 11. There is thus a continuous chain of cooperating metallic mounting elements extending from the end 12 of the body 11 to the base elements 29, 31.

In assembling this klystron, the cavity resonator 17 is first mounted on the body and the tube element assembly brought into the other end of the body and sealed therein. The guides 53 on the tube element assembly slide into engagement with the flanges 24 on the edges of the cavity resonator 17, thus producing an alignment of the cavity resonator in a longitudinal direction and also a transverse direction relative to the axis through the cathode and reflector.

The plates 18 and 18' forming the cavity resonator 17 are bowed outwardly slightly toprovide for temperature compensation of this klystron. In addition, the pair of U-shaped members 21 which are made of a material having a lower temperature coefficient of expansion than the steel cavity 17, such as molybdenum, are riveted to cavity 17 by rivets 19 as shown in Figs. 1 and 4. As the cavity resonator 17 expands upon heating, the gap space between grids 20 and 22 increases, to thereby compensate for the increased cavity size, due to the fact that the walls 18, 18 bow out slightly during expansion. Also, the U-shaped members 21 act to restrain movements of the cavity 17 radially from the beam axis, thus resulting in a further bowing out of the walls 18, 18'. Temperature compensation may be accomplished without the use of members 21 by constructing one of the plates18, 18 of a material having a higher temperature coeflicient of expansion than the other plate. For example, plate 18 may be made of copper while plate 18' is copper-plated steel. Plate 18 will tend to expand to a greaterdegree than plate. 18 and produce an increased outward buckling-of the plate 18' and an increase in the resonator gap spacing.

One fixed-tuned, reflex klystron made in accordance with the present inventionoperated at a frequency of approximately-10,525 megacycles, electronic tuning by reflector voltage variation permitting a small amount of tuning. i

Referring to Figs. 6 and 7 there is shown a waveguide flange adaptor for use in adapting the reflex klystron device shown in Fig. 1 for coupling to an output circuit having a waveguide flange. This adaptor circuit comprises. a waveguide flange 56 fixedly secured to a circular waveguide 57. A spring contact member having a plurality of longitudinal spring contact fingers 59' and a plurality of transverse spring contact fingers 61 is fitted within the end of thewaveguide adaptor such that when the klystron is plugged into the waveguide, the body of the reflex klystron makes good electrical contact with the outer waveguide 57 and waveguide flange 56. Adisk of dielectric material 58 such as Teflon is utilized to avoid variable contact of the fingers 61 with the waveguide flange 56. Longitudinal fingers 59 also aid in holding the klystron within the waveguide. The reflex klystron is properly aligned in the waveguide 57 by means of key 62 in the body 11. The waveguide flange 56 is a conventional size adapted to be coupled to conventional types of waveguide output circuits.

Fig. 8 discloses an embodiment wherein the klystron of Fig. 1 has brazed thereon a waveguide flange 63 suitable for connecting this reflex klystron to an output waveguide circuit.

Referring to Fig. 9 there is shown an embodiment in which a reflex klystron made in accordance with the present invention may be utilized with a tunable external cavity resonator thereby permitting frequency tuning. The window 14, window frame 15 and annular member 16 are not utilized in this embodiment but a waveguide flange 64 is brazed over the end 12 of the body 11 and is in turn brazed to another waveguide flange 65 having a window frame 66 and a ceramic window 67 secured therein. Brazed to the waveguide flange 65 is an external cavity resonator 68 provided with a screw tuner 69 in one wall thereof and a wave-trap type of mode suppressor 71 coupled through the other wall. A waveguide flange 72 suitable for mounting purposes is shown brazed to the outer end of the external cavity resonator. The theory of operartion of reflex klystrons utilizing fixed tuned internal cavity resonators heavily coupled to tunable external cavity resonators is well known in the art and will not be repeated in detail here. A reflex klystron constructed in accordance with the embodiment shown in Fig. 9 was tunable over the frequency range of 7,500 to 8,500 megacycles.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An electron discharge device of the velocity modulation type comprising a hollowevacuated body, the main axis of which extends between first and second vacuum sealed ends of the body, a mounting member mounted from said first end of the body, a pair of spaced-apart insulating plates fixedly secured on said mounting memher, the planes of said insulating plates extending perpendicular to the main axis of the body, tube elements including a cathode mounted from and between said insulating plates, a wave energy permeable window sealed in said second end of the body, a cavity resonator mounted from said second end of the body having an iris opening therein aligned with said wave energy permeable window in said second end of the body, said cavity resonator having guideways formed in the sides thereof, and a pair of metal resilient guide members fixedly mounted between said plates, said resilient guide members slidably fitting within said guideways on the sides of said cavity resonator for aligning said resonator with the tube elements including said cathode mounted between said plates and for holding said cavity resonator against vibration within said device.

2. An electron discharge device as claimed in claim 1 including a second cavity resonator mounted on said body and heavily coupled through said wave energy permeable window and iris opening to the first cavity resonator, and means in said second cavity resonator for tuning the frequency of operation of the electron discharge device.

3. An electron discharge device as claimed in claim 1 wherein said cavity resonator comprises a pair of outwardly-bowed cavity plates secured back to back to form the cavity resonator therebetween, said cavity plates being provided with outwardly extending flanged edges which serve to form said guideways.

4. An electron discharge device as claimed in claim 3 wherein said cavity resonator includes a resonator gap formed between said plates, and means for temperature compensating said cavity resonator including a metallic member of material having a lower coeflicient of expansion than the material of the cavity resonator plates fixedly secured on the plates between the bowed-out cavity-forming portion and the outer flanged edges, the cavity plates expanding more rapidly than the metallic member encircling the cavity during heating thus causing the plates to bow out and increase the gap spacing of the resonator gap within the cavity resonator.

5. An electron discharge device as claimed in claim 1 wherein said first end of the body is vacuum sealed by a ceramic insulation member and wherein said mounting member comprises a pair of metal thrust plates mounted on said ceramic member and extending within said device, -said resilient guide members fixedly mounted between said spaced-apart insulating plates also being fixedly mounted on said pair of thrust plates whereby a continuous metallic mounting chain extends from said cavity resonator through said resilient guide members and said thrust plates to said ceramic insulating member.

6. An electron discharge device of the velocity modulation type comprising a hollow evacuated body, the main axis of which extends between first and second vacuum sealed ends of the body, a mounting member mounted from said first end of the body, a pair of spaced-apart insulating plates fixed secured on said mounting member, the planes of said plates extending perpendicular to the main axis of thebody, tube elements including a cathode mounted from and between said insulating plates, the other end of said cylindrical body being closed by a wall having an iris opening therein, a cavity resonator mounted on said end wall having an opening therein aligned with the iris opening in said wall, a wave energy permeable window vacuum sealed on the wall over said iris opening, said cavity resonator having guideways formed in the sides thereof, and a pair of metal resilient guide members fixedly mounted between said insulating plates, said resilient guide members slidably fitting within said guideways on the sides of said cavity resonator for aligning said cavity resonator with the tube elements including said cathode mounted between said plates and for holding said cavity resonator against vibration within said device.

7. An electron discharge device as claimed in claim 6 including a second cavity resonator mounted on said body and heavily coupled through said wave energy permeable window and iris opening to the first cavity resonator and means in said second cavity resonator for tuning the frequency of operation of the electron discharge device.

8. An electron discharge device as claimed in claim 6 wherein said cavity resonator comprises a pair of outwardly bowed plates secured back to back to form the cavity resonator therebetween, said plates being provided with outwardly extending flanged edges which serve to form said guideways.

9. An electron discharge device as claimed in claim 8 wherein said cavity resonator includes a resonator gap formed between said plates, and means for temperature compensating said cavity resonator including a metallic member of material having a lower coeflicient of expansion than the material of the cavity resonator plates fixedly secured on the plates between the bowed-out cavity-forming portion and the outer flanged edges, the cavity plates expanding more rapidly than the metallic member encircling the cavity during heating thus causing the plates to bow out and increase the gap spacing of the resonator gap within the cavity resonator.

10. An electron discharge device of the velocity modulation type comprising a hollow evacuated body, the main axis of which extends between first and second vacuum sealed ends of the body, a ceramic insulating member sealing said first end of the body, a mounting means comprising a pair of thrust plates mounted on said insulating member and extending within said bod-1,6 pair of spaced-apart insulating plates fixedly secured on said pair of thrust plates the planes of said plates extending perdendicular to the main axis of the body and to the direction of said thrust plates, tube elements including a cathode mounted from and between said insulating plates, a wave energy permeable Window vacuum sealed in said second end of the body, a cavity resonator mounted from said second end of the body having an iris opening therein aligned with said wave energy permeable Window, andrneans mounted on .said insulating plates for aligning said resonator with the tube elements including said cathode mounted between said insulating plates and for holding said cavity resonator against vibration withinsaid device.

11. An electron discharge device as claimed inclaim 10 wherein said means mounted on said insulating plates for aligning said resonator with the tube elements comprises a pair of spaced-apart members resiliently tensioned against the cavity resonator, said resili nt members being fixedly secured to said thrust plates for vibrationless support.

12. An electron discharge device of the velocity modulation type comprising a hollow evacuated body including electron ,zbeam forming means therein and a cavity resona qr h ing i-aresona sap therein a g d with said electrombeam forming means therein, said cavity resonator being mounted by one of its sides in'said hollow evacuated'body and extending within-the body in cantilever fashion, said cavity resonator being formed of a vpair outwardly-bowed cavity plates mounted back to back and secured together to form the hollow evacuated cavity therewithin, said resonator gap being formed between said plates, and means for temperature compensating said cavity resonator including a metallic member of a material having a lower coefiicient of expansion than the material of the cavity resonator plates fixedly secured to the outer edges of said cavity resonator plates extending Within the evacuated body whereby the cavity plates expandlrnore rapidly than the metallic member encircling the cavity during heating thus causing the plates to bow out and increase the gap spacing of the resonator gap within the cavity resonator.

References Cited. in the file of this patent UNITED STATES PATENTS 2,439,908 Rigrod Apr. 20, 1948 2,900,561 Gorrnley Aug. 18, 1959 FOREIGN PATENTS 422,869 Great Britain Jan. 21, 1935 

